Lubricating oil



I Patented Aug. 22, i9

LUBRICA'EING OIL Frederick B. Downing, Penns Grove, N. 1., and Howard M. Fitch, Wilmington, Dot, assignors to E. I; du llont de Nemours & Company, Wil mington, DeL, a corporation of Delaware No Drawing. Application April 23,1942,

. Serial No. 440,200

- 18' Claims.

This invention relates to lubricating oils and particularly to lubricating oils designed for heavyduty service in internal combustion engines.

The production of a satisfactory lubricant, and particularly the production of a suitable lubricating oil for use in internal combustion engines, has presented a very dimcult problem and has been the subject of a great deal of research. The problems presented .are primarily due to deterioration of the lubricating oil under the conditions of use, which deterioration is primarily the result of oxidation accelerated by heat and the presence of the various metals in contact therewith. The products of such deterioration tend to form sludge, increase the viscosity of the oil, deposit on the parts of the engine and corrode sensitive bearing metals, such as those composed of alloys or mixtures of copper or lead, cadmium and nickel, silver and cadmium, and cadmium and tin. The increase in viscosity, the sludge and the deposits on the parts of the engine impede and may even arrest circulation of the lubricant. Corrosion of the sensitive bearing metals may proceed to such an extent as to cause mechanical failure of the engine. Accordingly, frequent and expensive changes of the oil, reconditioning of the engine and replacement of bearings are necessary. This is particularly true in so called heavy-duty service, that is, in the operation of trucks, buses, stationary and mobile power units and the like, where heavy loads are applied to the engines and deterioration of the oil is accelerated.

Many compounds have been proposed for addition to lubricating oils for the purpose of curing one or more of the defects of the ordinary petroleum lubricating oil. Amongst the materials which have been proposed for addition to lubricating oils are sulfur and sulfur compounds. Sulfur and its compounds are generally added to increase the film strength of the oils. This requires the addition of relatively large proportions of the sulfur and its compounds with sacrifice of other desirable properties of the oil. Usually the sulfur and its compounds tend to increase the corrosion of sensitive bean'ng metals and to have other deleterious efiects, so that they are not ordinarily used, except where high bearing pressures are bricating oils so as to take advantage of the detergent properties thereof for removing deposits from the parts of the engines and for maintaining the products oi. deterioration in suspension in the oils. Some of these materialsare alleged to inhibit deterioration of the oils, and others are alleged to inhibit corrosion of sensitive bearing metals. Such soaps and soap-like materials are organic compounds containing metals in chemical combination and may generally be referred to as organo-metallic compounds. Generally, the disclosures of the organo-metallic compounds in the art are quite broad and frequently indicate a large number of different metals as being suitable, some of them even indicating that copper compounds would be suitable. Copper and its compounds are notorious as catalysts for the oxidation of organic compounds. Those skilled in the art have generally found that many copper compounds, when employed in lubricating oils in the proportions ordinarily recommended for organo-metallic compounds, actually accelerate ox-' idation of the oils and/or corrosion of sensitive bearing metals. In the case of those copper compounds which apparently inhibit. the formation of sludge and like deterioration products, it has been generally necessary to add relatively large amounts of the copper compound to the oil in order to obtain practical and optimum results. However, such large amounts of such copper compounds generally accelerate corrosion of sensitive bearing metals. Also, while many compounds appear to have very desirable properties when subjected to some laboratory tests, they do not exhibit such properties when tested in an engine, particularly under conditions of heavy-duty service.

It is an object of this invention to provide new, improved and more stable lubricants. Another object is to provide lubricating oils for internal combustion engines and particularly for heavyduty service. A further object is to provide more stable lubricants which can be employed in internal combustion engines over longer periods of time with the formation of less deposits on the engine and with less corrosion of sensitive hearing metals. A still further object is to provide a lubricant which is more satisfactory in internal combustion engines under heavy-duty service. Other objects are to provide new compositions of matter and to advance the art.

The above and other objects of our invention may be accomplished by dissolving in a pctroleum lubricating oil, from to about 1000 parts of copper per one million parts of oil, here- 2 a,sse,co1

-. mimabbreviated r. P. 11., in as m. of oilsolubie non-ionogenic organic compounds of copperin epresenceofasmallproportiomsuiib cient impart substantial oil-stabilizing properties to the copper. of sulfur in the form of oilsoluble organic sulfur compounds. We have found that when such copper and sulfur compounds are employed in accordance with our invention, the deterioration of the lubricating oil is largely inhibited and lubricating oils of greatly improved properties are obtained. 1111s .is particularly apparent when such lubricating oils are employed in internal combustion engines under heavy-duty service, wherein the copper and the sulfur cooperate to stabilize the oil against deterioration so that the engines can be operated with such lubricating oils over long periods of time without causing objectionable increase in the viscosity ofthe oils, objectionable corrosions of sensitive bearing metals and the formation of objectionable amounts-cf deposits on the parts of the engines.

By an oilsoluble non-ionogenic copper compound we mean a copper compound soluble to readily be determined by observing whether or not copper is extracted by an aqueous solution of a weak acid from a solutionof the copper compound in a hydrocarbon solvent. Forexample, the following procedure is a satisfactory and convenient qualitative method for determining whether or not an organic copper compound is ionogenic. An approximately 1% solution of the copper compound in benzene is shaken vigorously for one minute at room temperature with an equal volume of a 10% aqueous solution of tartaric or citric acid. The mixture is then allowed to separate into an upper benzene layer and a lower aqueous layer. If the copper compound is lonogenic, it will be found that the copper has been removed from the benzene solution. This will be shown by a disappearance of the color of the copper compound from the benzene layer. It will also be shown by the presence of copper in the aqueous layer, the copper imparting a pale blue color to the aqueous solution. On

addition of excess ammonium hydroxide to a sample of the aqueous-layer, the characteristic deep blue color of cuprammonlum ions appears. This test is quite sensitive, as little as 50 P. P. M. ionogenic copper in the original benzene solution being suflicient to impart a perceptible blue color on addition of excess ammonium hydroxide to a sample of the aqueous layer. It the copper compound is non-ionogenic,-it will be found that substantially no copper has been removed from the benzene solution. The benzene layer will retain the characteristic color of the copper compound and the aqueous layer will not turn blue on addition of excess ammonium hydroxide.

Certain precautions must be observed in applying the above test. The test is so sensitive that copper will be found in the aqueous layer when testin non-ionogenic copper compounds containing, as impurities, small amounts of ionogenic copper compounds. In the case of a few ionogenic copper compounds, a green color will be obtained instead of blue on adding excess ammonium hydroxide to the aqueous layer. It the qualitative test appears to .be in any way abnormal or diflicult to interpret, it should be confirmed by a quantitative test. This is accomplishedbyanalyaingthebenzenesolutionofths copper for total c pper y i tivemethodsbothbeforeandaftertheabovedescribed extraction. Ifthe copper compound is ionogenic, it will be found that the benzene solution contains substantially no copper after extraction. If the copper compound is nonionogenio, it will be found that the benzene solution, after extraction, contains substantially as much copper as before extraction. When a mix- .ture ofionogenic and non-ionogenic copper compounds is tested, the amount of copper, remaining in the benzene solution after extraction, represents the amount oi non-ionogenic copper in the mixture, and the amount of copper removed by extraction, represents the amount of ionogenic copper in the mixture.

Itwillbeobvioustothoseskilledintheartoi analytical chemistry um, with suitable modiflcae tions, this quantitative test is capable of a variety of'applications. For example, extraction of a lubricating oil, containing copper compounds, with excess aqueous tartaricor citric acid will separate ionogenic (extracted) and non-ionogenic (not extracted) copper, and the amount'of each present in the oil can be quantitatively deter- .mined. If the lubricating oil is viscous it may be necessary to prolong the timed extraction or to employ a light hydrocarbon,-such as benzene or solvent naphtha, as a thinner in order to obtain quantitative extraction of the ionogenic copper.

It should be noted that we employ a weak acid, preferably tartaric acid or citric acid, in the above tests and conduct our extractions at room temperature, 2040 0. Strong acids, such as hydrochloric acid or sulfuric acid, will extract ionogenic copper but also tend to destroy the non-ionogenic copper compounds. Higher temperatures may be employed for the extraction, but these more severe conditions should not be used because they may give false results due to breaking down or altering the copper-containing molecules.

In our co-pending application Serial No. 440,- 202, filed April 23, 1942, we have disclosed the stabilization of lubricating oils by incorporating therein from 50 to about 500 P. P. M. of copper .together with from about 0.1% to about 0.5% of Y sulfur. In such application we have disclosed oil soluble compounds of copper generally, including ionog'enic as well as non-ionogenic compounds of copper and claim such class broadly and cer- I tain ionogenic compounds specifically.

' It has been found that the non-ionogenic copper compounds are superior to the ionogenic copper compounds as stabilizers for the lubricating oils and inhibitin corrosion of sensitive bearing metals. When the ionogenic compounds are employed, corrosion of sensitive bearing metals increases rapidly as the amount of copper in the oil is increased above 5*) P. P. M., and when amounts substantially above 500 P. P. M. are employed, frequently accelerate rather than inhibit such corrosion. On the other hand, non-ionogenic copper compounds may be employed in such amounts as to produce concentrations oi copper as high as 1000 P. P. M., and in some cases as high as 2000 P. P. M. or more and still materially inhibit corrosion of sensitive bearing metals by the oils.

Ionogenic copper compounds include copper derivatives of carboxylic acids, ketonates, phenates, and the purely inorganic salts of copper such as the sulphates, nitrates and halides. Complexes of these copper derivatives, with organic compounds, remain ionogenic. Some of the copcopper trithiocarbonates.

asaaoer per derivatives are quite effective in improving oil condition and engine cleanliness. However, they tend to increase rather than retard bear ing corrosion, unless their concentration in the oil is carefully controlled within quite narrow limits. Other ionogenic copper compounds are, in general, only moderately effective in improvtlcularly desirable oil-soluble copper mercaptides ing oil condition and engine cleanliness and retarding bearing corrosion. The non-ionogenic compounds on the other hand, are not only efiective to retard bearin corrosion in a wider range of copper but are also more effective in general in improving oil condition and engine cleanliness and in retarding bearing corrosion. Furtherore, the non-ionogenic copper compounds are more resistant to extraction from the oils by acids and alkalies during the processing and storage of the lubricating oils containing them.

The non-ionogenic copper compounds of our invention may be added to the oils in such proportion as to provide concentrations of copper as low as 50 P. P. M. and in some cases as high as 2000 P. P. M. or more. When employed in such proportions, the stability of the oils will be improved. In general, weprefer not to employ the copper compounds in proportions such as to provide copper in concentrationssubstantially above 1000 P. P. M., since the optimum results are obtained with concentrations below 1000 P. P. M. of copper and hence no additional benefit is obtained by employing concentration materially above 1000 P. P. M. Accordingly, the additionof more than 1000 P. P. M. of copper is wasteful and uneconomical. When the copper compound is employed in such proportion as to provide from 50 to about 200 P. P. M. of copper, it is generally essential to have present in the oil, at least 0.1% of sulfur in the form of oil-soluble, sulfur compounds. When the concentration of copper is increased above 200 P. P. M., such amount of sulfur is not necessary and when the proportion of copper approaches 500 P. P. M. and above, no sulfur may be necessary. However, it will usually be desired to have present in the oil, from about 0.1% to about 0.5% of sulfur. since such sulfur is effective to materially increase the stabilizing effect of the copper. Usually the opti-l mum results will be obtained when the concentration of copper in the oil is within the range of about 100 to about 500 P. P. M., and we preferably employ the copper compounds in such range. However, it should be noted that all oilsoluble copper compounds are not equally effecti-ve on a copper basis. The optimum concentration depends upon the nature of the copper compound, the nature of the lubricating oil employed, and the degree of stabilization desired and must bedetermined experimentally for each compound and each oil.

Some of the more important classes of nonionogenic copper compounds are copper mercaptides, copper dialkyl dithiocarbamates and Representative members of these classes, which have proved to be particularly desirable, are:

. Cuprous pentadecyl-8 mercaptide Cuprous cetyl mercaptide Copper-treated sulfurized dehydrated Occnol Cupric dibutyl dithiocarbamate Cupric diamyl dithiocarbamate Cuprous trithiocarbonate from pinene Cuprous pentadecyl-8 trithiocarbonate Cuprous octyl trithiocarbonate The preferred class of non-ionogenic copper are those derived from petroleum and petroleum products. Such mercaptides are comparatively cheap and readily available. The, methods of making mercaptans from petroleum products are well known in the art and include, among others, reacting halogenated petroleum fractions with sodium hydrosulfite, and reacting oleflns, derived from petroleum, with hydrogen sulfide. The mercaptans, naturally present in petroleum fractions or produced therein during refining processes, may also be isolated and employed for the preparation of copper mercaptides. Mercaptans from petroleum fractions are usually obtained as mixtures of mercaptans of varying chain lengths and structures. In the case of mixtures which contain mercaptans that'give insoluble copper salts, such mercaptans may be removed from the mixture by fractional distillation or by other methods prior to the preparation of copper mercaptides or, if desired, copper mercaptides may be prepared from the crude mixture and the oil-soluble copper mercaptides may then be isolated by dissolving them from the mixture into a lubricating oil or other hydrocarbon solvent. The mercaptans may be converted to COD-.- per mercaptides by treatment with a copper salt, such as cupric sulfate or cupric acetate, but it is preferable to employ a cuprous salt, such as ammoniacal cuprous chloride, because better yields of mercaptides will be obtained thereby. Crude mixtures/of oil-soluble copper mercaptides, derived from petroleum fractions and containing, as by-products or impurities, sulfur compounds such as organic sulfides, disulfides and the like, are suitable for addition to lubricating oils in accordance with our invention. Also, if desired, pure copper mercaptides, such as cuprous cetyl mercaptide, isolated from crude mixtures or made from pure hydrocarbons, such as cetene, obtained from petroleum, may be employed.

Particularly desirable compounds are the copper-=treated sulfurized unsaturated compounds. The copper-treated sulfurized unsaturated compounds are the products obtained by sulfurizing' an unsaturated compound, generally by treating it with sulfur with or without a catalyst at temperatures from about C. to about 200 C., and then treating such sulfurized product with metallic copper or a-copper salt. The preferred sulfurized unsaturated compounds, which are to be employed to produce the copper treated compounds, are the sulfurized unsaturated dehydrated alcohols prepared as disclosed in the copending application of F. B. Downing and R. G. Clarkson, Serial No. 440,201- filed April 23, 1942. The process, described in more detail in such application, comprises dehydrating unsaturated long chain alcohols in the-presence of catalysts. such as fullers earth at temperatures of from about 200 C. to about 300 C., whereby the alcohols are largely, converted to unsaturated ethers. The resulting dehydrated products are then sulfurized by treatment with sulfur in the presence of a catalyst at temperatures of from about 130 C. to about 200 C. By long chain, we mean compounds containing a carbon' chain of at least 10 carbon atoms. the sulfurized dehydrated unsaturated Ocenols." The term Ocenols" is generally employed by The'preferred compounds are hydrolytic reduction of unsaturated natural oils from vegetable,.fish and animal-sources, representatlve oils being sperm oil, beef tallow. lard oil, cottonseed oiL-olive oil, corn oil. rapeseed oil, menhaden oil, soyabean oil, linseed oil and Chinawood oil.

, The copper treatment of a sulfurlsed unsatur-.

4- ii,iuse,eei

disulfide, dicyclohexyl disulfide, dibensyi sulfide, dioctyl sulfide, dibutyl sulfone, pinane mercantan. pentadecan'e-thiol-B, triphenyl phosphine sulfide, -l,2.-bis (bemlthlo) ethane, dithloblsdiamyl formate, and dithiobis (dlbutyl thlo'formamide); Most lubricating oils contain an appreciable quantity of dissolved naturally occurring sulfur compounds. We have found that these naturally occurring sulfur compounds are ated compound has the dual advantage of introl I also effective when used in coniunction with conducing copper into the compound and of removing any unreacted or loosely-bound sulfur that may be present. The copper treatment may be accomplished at temperatures as low as 60' C. or

per compounds in accordance with our invention. Accordingly, we include the natural sulfur content in the oil when speaking of our preferred concentrations of sulfur. By an oil-soluble sulas high as 200 0., but temperatures of abouti-lsfur compound. we mean a compound that is 100 C. will usually be preferred. It is usually sufficient to stir the sulfurised compound'with powdered copper or a copper salt at a temperature of about 100' C. The amount of copper emwill depend on the amount of copper desired in the product and the nature of the sulfuriz'ed unsaturated compound. It is preferable to add the copper or copper salt slowly in small portions rather than in one batch. When the sulfurised 25 unsaturated compound contains appreciable quantities of unreacted or loosely bound sulfur, the first portions of copper added react with this sulfur and remove it, presumably as copper sulployed and the time and temperature. of heating I from elemental sulfur.

sumciently soluble in a lubricating oil to give a permanent solution at ordinary temperatures containing at least 0.10% sulfur. It should be noted that sulfur compounds behave differently The former enhance the stabilizing action of copper compounds, while the latter detracts from such stabilizing action. Accordingly; we specifically exclude elemental sulfur as a sulfur compound.

The products. obtained by sulfurizing unsaturated compounds, are particularly useful oilsoluble sulfur compounds, when employed in accordance with our invention. It willbe understood that an unsaturated compound is an fide, and only a little copper is introduced into organic compound which contains one or more the sulfurised unsaturated compoimd. When all the unreacted or looselybound sulfur has been removed, further additions of copper rapidly increase the copper content of the sulfurised unsatolefinic double bonds. These compounds include the sulfurised natural oils from vegetable, fish, andanimal sources, as well as .sulfurised synthetic unsaturated compounds. Sulfurized urated compound. Copper compounds, that may? sperm, lard, corn and menhaden oils and sulbe employed instead of copper powder, include cuprous chloride. cupric acetate, cupric oxide and cuprous cyanide. When the desired amount of furised terpenm may be mentioned .as examples of sulfurised natural oils. ,Examples of sulfurised synthetic unsaturated compounds include copper has been introduced into the sulfurised the products obtained by sulfurizing cetene,

unsaturated compound, the mixture is filtered H0 abietene,

or centrifuged from any copper sulfide or unreactedcopperandisthenreadyforuseasan additive for lubricating oils.

We do not know the exact structure of the oil-soluble copper compounds, obtained by treating sulfurized unsaturated compounds with copper or a copper salt. Oil-soluble compositions containing about 0.25-8.09, copper and about 840% sulfur are easily obtainable by this cyclohexene, dihydronaphthalene, menthene, dipentene, terpinene, terpinolene, oleyl alcohol, abietyl alcohol, methyl oleate and methyl abietate; Mixtures of sulfurized unsaturated compounds are equally suitable. The exact chemical structure of these sulfurized unsaturated compounds is not definitely known. It is known, however, that each double bond of such an unsaturated compound will ordinarily react with one, two, or three atoms of sulfur.

method and such compositions are high efiec- We prefer to employ compounds which contain tive when employed in accordance with our invention.

Another preferred class of non-ionogenic copper compounds comprises the copper dialkyl dinot more than one atom of sulfur for each double I bond present. Sulfur, inexcess of this quantity,

tends to function as elemental sulfur in detracting from the stabilizing action of copper comthiocarbamates. The members of this class, in .55 pounds and hence is undesirable.

refined oils will respond tothe treatment of our invention.

Oil-soluble sulfur compounds, that may be used in conjunction with copper compounds in accordance with our invention, include mercap- .tans, sulfides, disulfides, polysulfides, thioethers,

thiophenols, thi'ocarbamates, xanthates, thio acids, dithlo acids, sulphones, thioamides, and mixtures thereof. Specific examples of some of these types include dibenzyl disulfide, dipinane The preferred sulfurized unsaturated compounds to be employed in combination with the copper compounds, in accordance with our invention, are sulfurized unsaturated dehydrated =3 alcohols, prepared as described in the co-pending application of F. 13. Downing. and R. G. Clarkson, Serial No. 440,201 filed April 23, 1942.

It has been found that when lubricating oils are employed in internal combustion engines, the properties of the lubricating oils are materially aifected by the character of the fuel employed in the engine. It has been found that, when the motor fuel employed in an internal combustion engine contains tetra-ethyl lead, deterioration of t0 the lubricating oil and corrosion of sensitive bearing metals are materially increased. On the other hand, it has been found that, when. the lubricating oils of our invention'are employed in internal combustion engines operating on 18 motoroils containing tetra-ethyl lead, the effecaseaeei tiveness of the copper compounds in stabilizing the lubricating oils, is very materially increased. Also, our compounds are still very'efiective to inhibit corrosion of sensitive bearing metals even when the motor fuel contains substantial amounts of tetra-ethyl lead. The use of motor fuels, containing tetra-ethyl lead, in combination with the lubricants of our invention is disclosed more specifically and is claimed in the co-pending application of J. H. Fuller and J. R. Sabina, Serial No. e40,25o filed April 23, 1942, for Method of operating internal combustion engines.

The most satisfactory method of determining the stability of a lubricant in an internal combustion engine is by actual use of the lubricant in the engine. We employ the following engine test, which correlates well with results obtained in the field. Sim-cylinder 1940 and 1941 model Chevrolet engines (in some cases fitted with one copper-lead bearing) are operated on a block mounting at a speed of 3150 R. P. M. (equivalent to a road speed of 60 miles per-hour) against a load of 35 brake horse-power (equivalent to that obtained in road operation) applied by means of a dynamometer. The oil in the sump is maintained at 280 F. and the cooling jacket liquid at 200 F. The test is run for 66% hours (corresponding to road operation for 4000 miles), except in cases where the oil deterioration is so extensive that such lengthy operation is impractical. The degree of deterioration of the oil in this test corresponds directly to that obtained in equal periods of heavy-duty service and is indicative of that observed in longer periods of less severe service. The following ratings are employed to determine the stability of the oil and its effect on the engine. Samples of the oil used are removed from the crankcase at intervals and analyzed for total sludge (naphtha insolubles) and asphaltenes (chloroform solubles) by the method described in J. Ind. Eng. Chem., Anal. Ed. 6, 419 (1934) and for viscosity rise and neutralization number by the well-known A. S. T. M. methods. On the basis of these analyses, the condition of the oils is rated as excellent, good, fair, poor or bad. At the end of the run, the engine is disassembled, inspected and rated as to cleanliness. In the system of cleanliness rating employed, a clean engine would ence of large amounts of sludge or other\deposits or due to seizure of valve mechanisms or other moving parts. The copper-lead bearing is weighed before and at the end of the test to determine thep'loss in weight of sensitive bearing metals. The engine scores are more accurate and reproducible for relatively clean engines with scores of -100 than for dirty engines with scores of 50-70 because it is difilcult to determine the exact "'degreeof dirtiness of a very dirty engine. Conversely, low bearing corrosions of the order of 0.10 to 0.20 gram per bearing are more accurate and reproducible than high bearing corrosions of the order of 0.5 to 1.0 gram per bearing.

The following oils, each obtained from a diflerent refiner and selected as being typical of the types employed in ignition-engine lubrication, were used inthe tests.

action of the oil-soluble non-ionogenic copper compounds in improving oil' condition and engine cleanliness and retarding bearing corrosion, in an engine operating on motor fuel containing 1 cc. of tetra-ethyl lead per gallon of motor fuel. The corrosion of copper-lead bearings is given as the weight in grams lost by the bearing during the engine test. This figure also includes-the weight loss due to wear.

The amount of sulfur, naturally present in the oils used, was determined by the burnertest. In this test, a sample of oil is blended with 3 parts by weight of naphtha. The mixture is burned, and the combustion products are absorbed by a sodium carbonate solution. On addition of a barium chloride solution to the sodium carbonate solution, barium sulfate precipitates. From the quantity of barium sulfate obtained (corrected for traces of sulfur in the naphtha and reagents) the per cent sulfur present in the oil is calculated.

Team I Efiect of non-ionogenic copper compounds on oil condition, engine cleanliness and bearing cormsion P P. M

' Total Engine non-iono- Oil con- Cu-Pb 011 Additive genie 3 3," ggg; dition $3 corroeopgfir on rating rating sion None (avg. 4runs) o o. 24 66% Bad 55.0 1. 0s A Cupric dibutyl dithlocarbamate 120 0.27 66% o 91.5 0.97 A dn 200 0.29 66% Excellent 91.5 0. 20 A do 485 0.34 66% ...d0 92.5 0.33 A Cuprous trithiocarbonate from pinene 200 0. 27 66% .do 92. 0 0. 35 A Copper pentadecyl-S mercaptide plus pentadecy1-8 disulflde 120 0. 27 66% Good- 91.0 0.97 A Copper pentadecyl-S mercaptide plus pentadecyl-8 disulilde plus sulfurized dehydrated oeenol 120 0. 39 66% Excellent.. 89. 5 0. 57

score points. Points are deducted from this One hundred and thirty-nine parts of Ocenol,

score based on the quantity and quality of sludge 7 obtained by sodium and alcohol reduction of and other deposits in various parts of the engine. An engine with a. score of about 50 points by this system would be so badly fouled as to be in imminent danger of mechanical failure due to impaired lubricant circulation caused by the pressperm oil, was dehydrated by heating and stirring with 8 parts of fullers earth. The temperature of the mixture was slowly raised to 295 C., during 7 hours. After stirring for 3 hours longer at 295 C., dehydration was essentially complete.

The mixture was then cooled to 200 C. and sulfurized. by stirring with 15 parts of sulfur for 3 hours at 195-205 C. This product is representative of the sulfurized unsaturated compounds disa closed and claimed in the co-pending application of I". B. Downing and R. 0.0mm, hereinbefore referred to. The product, thus obtained, was

then copper treated. This was accomplished by slowly adding 16 parts of copper powder with stirnol" as a dark-red oil containing 7.43% S and 0.63 Cu. This material is designated I. Two other samples of copper-treated sulfurized dehydrated "Ocenol," prepared in a similar manner, are designated II and III. 11 contained 8.77% S and 1.19% Cu, and III contained 8.89% S and 2.15%- Cu. These materials were tested in Chevrolet engines, as previously described, and the results of the tests are given in Table 11.

Tears: II

tion primarily, if not entirely, through protec-l tion of the oil from the deleterious effects of oxidation during use in the engine. The concentrations'employed are insui'llcient to produce any worthwhile detergenoy or lubricity in the oil, and the non-ionogenic copper compounds appear to function as antioxidants rather than as detergents or illm strength improvers. Furthermore, the lubricating oil compositions disclosed are free-flowing liquid lubricants suitable for crankcase use and are not greases.

While we have disclosed the preferred embodimentsof our invention, it will be understood that such specific embodiments are given for illustrative purposes only and that various modifications may be made therein without departing from the spirit or. scope of our invention. For example, we have disclosed generally, the use of single copper compounds. It will be apparent that mixtures of any two or more oil-soluble non-ionogenic copper compounds of our invention may be employed, if desired. Accordingly, we intend Efiect of copper-treated. sulj'nrized dehydrated "Ocenol" on oil condition, engine cleanliness and bearing corrosion. g

Engine P. P. M. Total Oil con- Cu-Pb 011' Additive Onln Y roant Egg. dition 325 corrooil inoil rating rating slon A..-" e 0 0.23 00% Bad 50.5 1.05 A 2.06%I-.- 129 0.88 00% Excellent. 94.0 0.60

B None"--. 0 0.00 33% Bad 63.0 v 1.20 B 2.06%I--- 129 0.21 06% Excellent. 94.6 0.08

0..... None 0 0.26 33% Bad 60.6 0.00 0..... 2.05931... 120 0.41 00% Good-.-.. 00.0 0.11

D Nono----- 0 0.01 sag Bad 53.0 D.-.-- 1.11%n- 0.40 00 0 0..--.- 85.6 a---" Nona 0 0.10 00 Bad 42.0 1 0.85 r: 0.10% m. 104 s 0.20 00% Good 820 can 1* None---.. 0 0.11 00% Bad 00.0 1.00 r 2.00%-..- s 120 0.20 00% Good 83.0 0.10

1 Oil D was non-corrosive.

The tests, the results of which are shown in Tato cover our invention broadly as in the appended ble 11 above, were conducted with the engines claims. operating on gasoline having incorporated We claim:

1. Alubricant comprisingapetroleum lubricattherein 1 cc. per gallon of tetra ethyl lead as a well known standard commercial composition which also contained alkyl halides. 1

.While the stabilizing action of non-ionogeniccopper compounds on lubricants for. internal combustion engines is most striking in so-called heavy-duty service, a similar effect is also obtained in less severe service. Internal combustion engines in which these additives may be employed with beneficial results include engines designed for use in passenger automobiles, trucks,

tanks, buses, tractors, aircraft and stationary and semi-stationary power plants. Furthermore,

' cosity index improvers, thickeners, detergents and the like. V

We do not know the exact mechanism by which the non-ionogenic copper compounds function as lubricant stabilizers. They appear to funcing oil having dissolved therein from 50 to 1000 P. P. M. of copper in the form of an oil-soluble non-ionogenic organic compound of copper and a small proportion, suflicient to impart substantial oil-stabilizing properties to the copper, of sulfur in the form of oil-soluble organic sulfur compounds.

2. A lubricant comprising a petroleum lubricating oil having dissolved therein from 50 to 1000 P. P. M. of copper in the form of an oil-soluble non-ionogenic organic compound of copper and from about 0.1% to about 0.5% of sulfur in the form of oil-soluble organic sulfur compounds.

3. A lubricant comprising a petroleum lubricating oil having dissolved therein from 50 to 1000 P. P. M. of copper in the form of an oil-soluble non-ionogenic organic compound of copper and from about 0.1% to about 0.5% of sulfur in the form of oil-soluble organic sulfur compounds, at least a substantial proportion of which are sulfurized unsaturated organic compounds containing a maximum of one'sulfur atom for each effective double bond.

4. A lubricant comprising a petroleum lubricating oil having dissolved therein from 50 to 1000 P. P. M. of copper in the form of an oil-soluble non-ionogenic organic compound of copper and from about 0.1% to about 0.5% of sulfur in the form of oil-soluble organic sulfur compounds, at least a substantial part of which are sulfurized unsaturated ethers containing a maximum of one sulfur atom for each effective double bond.

5. A lubricant comprising a petroleum lubricating oil having dissolved therein from 50 to 1000 P. P. M. of copper in the form of an oil-soluble non-ionogenic organic compound of copper and from about 0.1% to about 0.5% of sulfur in the form of oil-soluble organic sulfur compounds, at

least a substantial proportion of which are sulfurized unsaturated dehydrated alcohols obtained by the reduction of an unsaturated natural oil which sulfurized dehydrated alcohols contain a maximum of one sulfur atom for each effective double bond.

6. A lubricant comprising a petroleum lubricating oil having dissolved therein from 50 to 1000 P. P. M. of copper in the form of an oil-soluble copper mercaptide and a small proportion, sufficient to impart substantial oil-stabilizing properties to the copper, of sulfur in the form of 011- soluble organic sulfur compounds.

7. A lubricant comprising a petroleum lubricating oil having dissolved therein from 50 to 1000 P. P. M. of copper in the form of an oil-soluble copper mercaptide of an aliphatic mercaptan and a small proportion, sufiicient to impart substantial oil-stabilizing properties to the copper, of sulfur in the form of oil-soluble organic sulfur compounds.

organic compound is a copper-treated sulfurized dehydrated mixture of unsaturated long chain alcohols derived from an unsaturated fatty oil, the organic compound being dissolved in the lubricating oil in such proportion that the oil contains dehydrated mixture of unsaturated long chain alcohols derived from sperm oil, the organic compound being dissolved in the lubricating oil in such proportion that the oil contains from 50 to 500 P. P. M. of copper and from about 0.1% to about 0.5% sulfur.

13. A lubricant comprising a petroleum lubricating oil having dissolved therein from 50 to 1000 P. P. M. of copper in the form of an oilsoluble dialkyl dithiocarbamate of copper and a small proportion, sufficient to impart substantial oil-stabilizing properties to the copper. of sulfur in the form of oil-soluble organic sulfur compounds.

14. A lubricant comprising a petroleum lubricating oil having dissolved therein from 50 to 1000 P. P. M. of copper in the form of an oil soluble dialkyl dithiocarbamate of copper in which the alkyl groups contain a total of at least six carbon atoms and from about 0.1% to about 0.5% of sulfur in the form of-oil soluble organic sulfur compounds.

15. A lubricant comprising a petroleum lubricating oil having dissolved therein from 50 to 1000 P. P. M. of copper in the form of cupric dibutyl dithiocarbamate and from about 0.1% to about 0.5% of sulfur in the form of oil-soluble organic sulfur compounds.

16. A heavy-duty internal combustion engine lubricant comprising a petroleum lubricating oil having dissolved therein from 50 to 1000 P. P. M.

of copper in the form of an oil-soluble non-ionnon-ionogenic copper-treated sulfurized unsaturated organic compound wherein both the copper and the sulfur are chemically combined, there being a maximum of one sulfur atom for each double bond in the compound, the organic compound being dissolved in such proportion that the oil contains from to about 500 P. P. M. of copper and from about 0.1% to about 0.5% sulfur.

10. A lubricant comprising a petroleum lubricating oil, normally containing substantially less than 0.5% sulfur, and having dissolved therein a non-ionogenic organic compound containing chemically combined copper and sulfur, which organic compound is a copper-treated sulfurized ogenic organic compound of copper and a small proportion, suficient to impart substantial oilstabilizing properties to the copper, of sulfur in the form of oil-soluble organic sulfur compounds.

gg ganic compound wherein both the copper and the dehydrated mixture of unsaturated long chain alcohols, the organic compound being dissolved in the lubricating oil in such proportion that the oil contains from 50 to 500 P. P. M. of copper and from about 0.1% to about 0.5% sulfur.

11. A lubricant comprising a petroleum lubricating oil, normally containing substantially less than 0.5% sulfur, and having dissolved therein a non-ionogenic organic compound containing chemically combined copper and sulfur, which sulfur are chemically combined, there being a mum of one sulfur atom for each double bond in the compound, the organic compound being dissolved in such proportion that the oil contains from 50 to about 500 P. P. M. of copper and from about 0.1% to about 0.5% sulfun.

18. A. lubricant comprising a petroleum lubricating oil having dissolved therein from 50 to 1000 P. P. M. of copper in the form of cup'rous pentadecyl-8 mercaptide and from about 0.1% to about 0.5% of sulfur in the form of oil-soluble organic sulfur compounds.

FREDERICK n. powma. HOWARD M. r'rrcn.

17. A heavy-duty internal combustion engine 

